In the field of petroleum development, geological exploration, etc., a core holding system shall be used in the laboratories to hold cores drilled from stratums of a region to be researched. In the prior art, the core holding system has the standard sizes of 25 mm, 38 mm, 100 mm, etc. But in the actual coring process, the cores drilled from the stratums may not completely meet the standard sizes of the core holding system in the prior art, due to the reasons of the equipment or the personnel operations. The core diameter may be larger or smaller than the standard size of the core holding system, thus some of the cores cannot be held by the core holding system. The core drilling usually costs a lot of manpower and material resources. Therefore, it is a problem to be urgently solved to ensure that all of the cores drilled from the stratums can satisfy the usage by the core holding system.
In addition, when the cores are to be tested or researched, they shall be placed under the high temperature condition of the simulation stratum, which requires the holder that holds the cores to be placeable into the constant-temperature equipment. But the core holding system in the prior art has a large volume and cannot be placed into the constant-temperature equipment.